Pressure indicating wrench



15 a, 1936. ER 2,063,622

PRESSURE INDICATING WRENCH Filed Feb. 15, 1934 I INVENTOR. Karl P/ZZfff,

ATTORNEYS.

human. a iaae UNITED STATES PATENT, OFFICE ran-assume mmca'rme wnnnon m1Pfeifler, mm, man. Application February 15, 1934, Sel'lfl No-7l1,325 2Claims. (01. 285-1) My'invention relates to wrenches and particularly toa wrench which indicates the amount of pressure which is applied to astud, nut'or like element.

Power wrenches have been employed heretofore wherein a fluid wasutilized as a means for applying a pressure to tighten a nut, screw orbolt. It is'also known that certain friction type of wrenches have beenemployed which can be set to apply a predetermined pressure above whichno force can be exerted.

In practicing the present invention, I employ a wrench whereon anyamount of pressure desired may be applied, a gauge being employed torecord the amount of pressure so that the operator may be able to applythe same pressure to others of a series of studs, screws, bolts, nuts orlike elements.

Accordingly, the main objects of my invention are; to provide a wrenchby which a pressure is applied to a nut engaging end through pressuremeans which indicates the amount of pressure exerted; to provide awrench having a head which may be adjusted to various positions relativeto the wrench so that the wrench may be operated through a limited spaceto tighten an element; to provide a stop between the actuated andoperated end of the wrench so that it may be employed to loosen screws,nuts or bolts once they have been set; to provide a wrench whichaccurately indicates the pressure applied to tightening a nut, stud orthe like, so that a series thereof may be tightened an equal amount, andin general to provide a wrench which is rigid in construction,

accurate in indicating the pressure applied, and

which is economical of use and manufacture.

Other objects and features of novelty of my invention will be eitherspecifically pointed out or will become apparent when referring for abetter understanding of my invention to the following description takenin conjunction with the accompanying drawing, wherein:

Figure 1 is a plan view, partly in section, of a wrench embodyingfeatures of my invention, and

Fig.2 is a view in side elevation of the structure illustrated in Fig.1, with parts in section.

In the figures, I have illustrated a bracket 5 having an extending boss6 and spaced oppositely extending lugs I. Upon the boss is rotatablymounted a hub 9 having an extending arm 9 thereon and an extendinghandle I I by which the wrench is operated, A hand grip I2 may beprovided on the end of the handle II, as illustrated in Fig. l. The endof the boss 5 is provided with a threaded stud l3 upon which a washer I4is retained by a nut I! to retain the hub 8 on the boss 9 for pivotalmovement.

The arm 9 is provided with a bifurcated end portion IE to which a pistonrod ll of the piston I8 is loosely pivoted'by a pin l9. Some play is 5provided between the end of the rod l1 and the pin I!) to permit thearcuate movement of the arm 9 without binding the piston I3. The pistonI9 is provided with suitable sealing rings or. packings 29 to preventthe flow of fluid thereby. The 10 piston is sealed within the walls of acylinder 2| which is fixed to the bracket 5 by suitable means hereinshown .as bolts 22. The opposite end of the cylinder is provided with anoutlet opening 23 to which a gauge 24 is supported by a suitable conduit25. A fluid 2B, preferablyoil, is intro-' duced into the cylinderthrough an opening 21 sealed by a plug 28. The bracket element 5 carriesa fixed stop 29 which is engaged by a stop 3| on the arms 9.

The boss 6 is provided with a cylindrical aperture 32 in which acylindrical projection 33 of a driving head 34 is positioned forlongitudinal movement. The longitudinal movement is limited by a ball 35operating in a slot 36 con tained within the wall of the cylindricalprojection 33. A spring 31 is disposed between the head 34 and thebracket 5 for the purpose of biasing the head 34 outwardly to haveprojections 39 on the head 34 clear the projections l on the bracket 5.The projections 1 and 38 interfit with each other and in this manner thetool and head are separated and revolved to a new mated position so thatthe head may be turned through a small degree repeatedly withoutremoving the wrench from the element to be tightened. The end of thehead 34 terminates in a square shank 39 having a spring pressed ball 4itherein for receiving a nutengaging element which is retained on theshank 39 by the ball 4i in a conventional manner. It 40 is to beunderstood that a ratchet and pawl can be substituted for theprojections l and 38 when desired.

The wrench was constructed primarily to be used in the automotive tradefor the purpose of applying an equal force to all of the studs or nutswhich retain the cylinder head on the engine block. It was found fromactual test that the uniform tightening of the clamping element of thehead is desirable to uniformly distribute stresses over the engineblock, the cylinders of which were found to warp as much as .003 to .004out of round when the head is attached.

When the wrench is employed with the leveling and clamping plate as setforth in the patent of K. W. Connor, No. 2,006,158 issued June 25, 1935,

the assignee of the exclusive licenses under the to a circular formwhile under the service stress condition. After the grinding and thestresses are relieved, the cylinders will not be exactly round but willbe returned to cylindrical shape when the head is screwed down with thesame pressure as was applied to the clamping plate be had that thecylinders will be exactly round when the cylinder head is screwed uponthe engine block.

The present wrench is rigid in construction and accurate in indicatingthe torsional pull applied as an arbitrary number or in foot-poundsload. I have shown an ordinary gauge which indicates the pressure as anarbitrary number and not the exact foot-pound load applied in torsion tothe nut. When desired'a dial may be employed which reads the actualtorsional loading in foot-pounds applied to the nut or stud. Since,however, the wrench in the present instance is employed to apply asimilar load on all of a series of nuts, the mere indicating of thepressure gives accurate indication of the similarity of force appliedthereto.

While I have described and illustrated but a single embodiment of myinvention, it will be apparent to those skilled in the art that variouschanges, additions, omissions and substitutions may be made therein,such for instance, as using a cylinder with a vein therein whichoperates through a liquid to turn a vein and the nut engaging headand-having a gauge mounted directly thereabove in direct communicationwith the engaging portion having a cylinder secured thereto, the axis ofthe cylinder being disposed substantially tangential to a circle whosecenter lies in the axis of said element engaging portion, an operatinghandle plvotally connected to said element engaging portion coaxiallytherewith, a piston in said cylinder operatively connected with saidhandle and a fluid pressure gauge communicating with the interior ofsaid cylinder to register the torque applied to said element engagingportion by said handle.

2. An indicating wrench including an element engaging portion having aportion adapted toengage an element to be rotated, said element engagingportion having a cylinder secured thereto, the axis of the cylinderbeing disposed substantially tangentially to a circle whose center liesin the axis of said element engaging portion, an operating handlepivotally connected to said element engaging portion coaxiallytherewith, a piston in said cylinder, a piston rod connected to saidpiston and operatively engaging said handle, fluid within said cylinderfor transmitting torque applied by said handle to said element engagingportion and a pressure gauge in communication with the interior of saidcylinder for indicating the pressure of the fluid therein andconsequently the magnitude of such torque.

KARL PFEIFFER.

